Laying dust in coal mines



Patented Nov. 19, 1940 UNITED STATES PATENT OFFICE LAYING DUST IN COAL LIINES No Drawing. Application March 1, 1939, Serial No. 259,285

4 Claims. (o1. 160-2) This invention relates to laying dust in coal mines; and it comprises a method of preventing and laying dust in coal mines-wherein the mine workings are sprayed with a mixture or emulsion s of petroleum oil and water in a proportion of at least 50 per cent water and at least per cent 011; all as more fully hereinafter set forth and as claimed.

The problem of coal dust in coal mines is a in serious one. Various materials and methods have been proposed to overcome the dust hazard in coal mines, but the problem remains. Heretofore the most acceptable method has been, in. the use of rock dust to mingle with the coal dust 15" and thus to prevent explosions- This method has obvious disadvantages. .The rock dust adds spray the workings with oil in admixture with suflicient water to make the oil spray noninflammable. An emulsion of oil in about twice its volume of water is a most eil'ectivespraying fi liquid. The oil wets the coal and penetrates the v v.coal particles. The water does not wet the coal and evaporates or runs ofi, leaving the coal coat ed with oil. The particles clod together and dusting is prevented.

a Spraying the coal faces with both 011 and water in homogeneousadmixture prevents formation of dust in cutting the coal with machines,

the water, as I have found, removing the fire hazard due to the oil spray. Also spraying coal 3'; dust already formed'with such a mixture lays the dust and overcomes the dust explosion hazard.

The mixture of oil and water can be formed invarious ways. The oil should be a petroleum 40 oil of suitable gravity and viscosity and of relatively low volatility and the water should be in a proportion of at least per cent of the mixture for adequate safety from inflammability. A ratio of 2 parts onto 3 parts water is recom- 41 mended. The object being to coat the coal with 'oil, a proportion of less than 20 per cent oil in the mixture is not advisable. The proper relative proportions of oil and water will depend on the extent of oil coverage desired and the rapid- 50 ity with which the surface to be sprayed is traversed by the spray. When the spray rapidly traverses the surfaces to be. covered the proportion of water in the mixture is kept near the minimum requiredfor safety, but, when the spray is slowly applied, considerably more water may be used with the oil. The oil in the 011-,

water mixture impregnates the coal and to a large extent prevents dusting. A

The oil-water mixture may be formed by feeding water and oil from separate sources to a common spray nozzle in the proper ratio. However, it is usually more expedient to form an emulsion of oil and water and to spray the emulsion. For spraying purposes, an emulsion of oil-in-water has been found most effective and safe, but emulsions of water in oil may be used if desired. With most oils it is necessary to use an emulsifying agent to form an emulsion of any permanence. Sufllcient permanence for most spraying purposes is afiorded by preparing an emulsion of oil and water held together by gum ghatti or by a sodium sulfonate as an emulsifying agent. Where, greater permanence is desired, for instance whre it is desired to"prepare'and store quantities of a spraying emulsion for a considerable time prior to use, small portions of oleic acid and ethylene glycol may be added with a sodium petroleum suli'onate to give the emulsion greater permanence or stability. Various other emulsifying and stabilizing agents for'forming oil and water emulsions are known and may be used. t

In preparing spray emulsions, petroleum distillates of low volatility are usually employed having a gravity varying between 20.0 and 25.0 A. P. I. and varying in viscosity between and 650 seconds S. U. V. at 100 F.

A particularly safe and efiective emulsion made by blending 400 gallons of a petroleum distillate of 20.0 A. P. I. gravity and 620 seconds S. U. V. viscosity at 100 F. with 600 gallons of water, using 40 gallons or 4 per cent of a sodium petroleum sulfonate as an emulsifying agent. This will give a semi-permanent emulsion, but where greater permanence is desired the emulsion may be further stabilized by incorporating therein 8 gallons oleic acid and 8 gallons ethylene glycol. I

In spraying oil and water mixtures or emul-- sions in mines the following procedure is recommended: I

The equipment preferably comprises -a highpressure motor driven rotary pump connected by suitable piping and valve controls to several spray nozzles preferably of the impingement type disclosed in the U. '8. 'Patent to Pigott No. 2,058,823. This type of nozzle afl'ords good dispersion of fluid particles. The nozzles may be arranged to direct the spray upward, downward and on both sides of a vehicle so that in spraying a tunnel one traversal will complete the spray treatment of the floor, walls, and ceiling. The

' late the contents through the pump without passage to the nozzles. The oil-water mixture may be circulated several times through the pump in order to obtain uniform dispersion in the mixture. When using emulsifying agents, very little agitation is required to emulsify the oil and water prior to spraying.

When less extensive spraying is required, a single nozzle or small group of nozzles may advantageously be mounted on the end 01' a highpressure flexible hose connected to a source of spray mixture under pressure. This affords portable equipment i'or manual operation within a restricted range.

The invention is particularly useful in spraying the cutting bars and cuttings during operation oi-an undercutting machine or the like to allay dust as it is formed in the cutting operation. Thus, the spraying equipment may be associated with a cutting machine and the spray nozzle situated so as to spray the surfacesundergoing cutting.

What I claim is:

1. A method of preventing and laying dust in coal mines which comprises spraying the mine workings with a mixture of petroleum oil of low volatility and water" in a volume proportion of the mixture at least 50 per cent water and at least 20 per cent oil.

2. A method of preventing and laying dust in coal mines which comprises spraying the mine workings with a liquid emulsion containing petroleum oil of low volatility and water in a volume proportion of at least 50 per cent water and atleast 20 per cent oil.

3. A method of preventing and laying dust in coal mines which comprises spraying the mine workings with a liquid emulsion containing petroleum oil of low volatility and water in a volume proportion of at least 50 per cent water and at least per cent oil and containing a sodium sulfonate 'as an emulsifying agent. i

4. A liquid spray for. preventing and laying dust in coal mines consisting essentially of an emulsion of petroleum oil of 20 to A. P. I. 

